In v1.25-49-gf6746275, we adjusted the default TCP keepalive
value for clients from 10s to 60s. The motivation for doing so
was to allow the system to withstand an - at that time - unknown
networking issue that caused intermittent fencing/disconnects.
It was later determined that lock recovery stalls were the culprit,
and those were largely addressed by ca. v1.26-21-gf0c79966 which
fixes the issue at the root of the problem. The increase from
10s to 60s however was not reverted.
We are now seeing issues when scoutfs is deployed as multiple
filesystem mounts on a cluster where e.g. the server is dropped
for a fencing test - causing a non-leader node to take over from
the fenced server. It will issue new fence requests for clients
that were previously connected in 30 seconds. But with a 60sec
TCP timeout value, any client that is still up will wait silently
for the fenced server, until the new leader fences them. This leaves
the cluster degraded in case of a 3-node quorum.
The precise timeline:
- 0sec: nmcli down on node0
- 10sec: new election issued, node1 wins, node2 remains follower
- 15sec: node0 fenced (quorum old leader fence)
- 45sec: node1 fences clients that failed to recover
never reached:
- 60sec: node2 client reconnect due to TCP timeout
In our scoutfs testing we never see this because we just call umount
in our testing script unconditionally. In a multi-fs scenario with
real fencing this is never done, and so the cluster degrades almost
entirely consistently.
Drop the value to 24sec. The new value is well below the highest
acceptable value: 45sec. We don't want to lower it too much, and we
also don't want it to be a multiple of 15/10 to avoid concurrent
intervals causing "flapping" or waves of events excluding. 24s fits
well between the minimum of 15 and maximum of 45 and isn't a straight
factor or multiple of 10, 15, or 30.
Test results: on my 3-node 3-fs setup, this 100% recovered all 3
fs's without degrading the cluster. In 1/20 tests I had to re-start
2 nodes (a "flap") in succession to recover. In the rest of the tests,
the cluster recovered as expected.
Signed-off-by: Auke Kok <auke.kok@versity.com>
The use of the VM shrinker was a bad fit for locks. Shrinking a lock
requires a round trip with the server to request a null mode. The VM
treats the locks like a cache, as expected, which leads to huge amounts
of locks accumulating and then being shrank in bulk. This creates a
huge backlog of locks making their way through the network conversation
with the server that implements invalidating to a null mode and freeing.
It starves other network and lock processing, possibly for minutes.
This removes the VM shrinker and instead introduces an option that sets
a limit on the number of idle locks. As the number of locks exceeds the
count we only try to free an oldest lock at each lock call. This
results in a lock freeing pace that is proportional to the allocation of
new locks by callers and so is throttled by the work done while callers
hold locks. It avoids the bulk shrinking of 10s of thousands of locks
that we see in the field.
Signed-off-by: Zach Brown <zab@versity.com>
The default TCP keepalive value is currently 10s, resulting in clients
being disconnected after 10 seconds of not replying to a TCP keepalive
packet. These keepalive values are reasonable most of the times, but
we've seen client disconnects where this timeout has been exceeded,
resulting in fencing. The cause for this is unknown at this time, but it
is suspected that network intermissions are happening.
This change adds a configurable value for this specific client socket
timeout. It enforces that its value is above UNRESPONSIVE_PROBES, whose
value remains unchanged.
The default value of 10000ms (10s) is changed to 60s. This is the value
we're assuming is much better suited for customers and has been briefly
trialed, showing that it may help to avoid network level interruptions
better.
Signed-off-by: Auke Kok <auke.kok@versity.com>
Add support for project IDs. They're managed through the _attr_x
interfaces and are inherited from the parent directory during creation.
Signed-off-by: Zach Brown <zab@versity.com>
Add a bit to the private scoutfs inode flags which indicates that the
inode is in retention mode. The bit is visible through the _attr_x
interface. It can only be set on regular files and when set it prevents
modification to all but non-user xattrs. It can be cleared by root.
Signed-off-by: Zach Brown <zab@versity.com>
We're about to add new format structures so increment the max version to
2. Future commits will add the features before we release version 2 in
the wild.
Signed-off-by: Zach Brown <zab@zabbo.net>
Add a mount option for the amount of time that log merge creation can
wait before giving up. We add some counters so we can see how often
the timeout is being hit and what the average successfull wait time is.
Signed-off-by: Zach Brown <zab@versity.com>
Add mount and sysfs options for changing the quorum heartbeat timeout.
This allows setting a longer delay in taking over for failed hosts that
has a greater chance of surviving temporary non-fatal delays.
We also double the existing default timeout to 10s which is still
reasonably responsive.
Signed-off-by: Zach Brown <zab@versity.com>
Make mount options for the size of preallocation and whether or not it
should be restricted to extending writes. Disabling the default
restriction to streaming writes lets it preallocate in aligned regions
of the preallocation size when they contain no extents.
Signed-off-by: Zach Brown <zab@versity.com>
Add support for the POSIX ACLs as described in acl(5). Support is
enabled by default and can be explicitly enabled or disabled with the
acl or noacl mount options, respectively.
Signed-off-by: Zach Brown <zab@versity.com>
Add a mount option to set the delay betwen scanning of the orphan list.
The sysfs file for the option is writable so this option can be set at
run time.
Signed-off-by: Zach Brown <zab@versity.com>
We had previously started on a relatively simple notion of an
interoperability version which wasn't quite right. This fleshes out
support for a more functional format version. The super blocks have a
single version that defines behaviour of the running system. The code
supports a range of versions and we add some initial interfaces for
updating the version while the system is offline. All of this together
should let us safely change the underlying format over time.
Signed-off-by: Zach Brown <zab@versity.com>
Add the .totl. xattr tag. When the tag is set the end of the name
specifies a total name with 3 encoded u64s separated by dots. The value
of the xattr is a u64 that is added to the named total. An ioctl is
added to read the totals.
Signed-off-by: Zach Brown <zab@versity.com>
Add the data_alloc_zone_blocks volume option. This changes the
behaviour of the server to try and give mounts free data extents which
fall in exclusive fixed-size zones.
We add the field to the scoutfs_volume_options struct and add it to the
set_volopt server handler which enforces constrains on the size of the
zones.
We then add fields to the log_trees struct which records the size of the
zones and sets bits for the zones that contain free extents in the
data_avail allocator root. The get_log_trees handler is changed to read
all the zone bitmaps from all the items, pass those bitmaps in to
_alloc_move to direct data allocations, and finally update the bitmaps
in the log_trees items to cover the newly allocated extents. The
log_trees data_alloc_zone fields are cleared as the mount's logs are
reclaimed to indicate that the mount is no longer writing to the zone.
The policy mechanism of finding free extents based on the bitmaps is
ipmlemented down in _data_alloc_move().
Signed-off-by: Zach Brown <zab@versity.com>
Introduce global volume options. They're stored in the superblock and
can be seen in sysfs files that use network commands to get and
set the options on the server.
Signed-off-by: Zach Brown <zab@versity.com>
Update the man pages with descriptions of the new mkfs -Q quorum slot
configuration and quorum_slot_nr mount option.
Signed-off-by: Zach Brown <zab@versity.com>
mkfs: Take two block devices as arguments. Write everything to metadata
dev, and the superblock to the data dev. UUIDs match. Differentiate by
checking a bit in a new "flags" field in the superblock.
Refactor device_size() a little. Convert spaces to tabs.
Move code to pretty-print sizes to dev.c so we can use it in error
messages there, as well as in mkfs.c.
print: Include flags in output.
Add -D and -M options for setting max dev sizes
Allow sizes to be specified using units like "K", "G" etc.
Note: -D option replaces -S option, and uses above units rather than
the number of 4k data blocks.
Update man pages for cmdline changes.
Signed-off-by: Andy Grover <agrover@versity.com>
Auke Kok
Zach Brown
Bryant G. Duffy-LyandZach Brown
Andy GroverandZach Brown